Typical spray delivery systems include aerosol bottles, hand sprayers, and motorized and air driven paint sprayers. Aerosol bottles require special propellants and have environmental issues. Hand sprayers are typically limited to light liquids such as cleaning fluids that have a similar viscosity to water. Paint sprayers typically require a compressed air source or electric cord, making them too large and awkward for many applications. The aerosols and paint sprayers typically produce small droplet sizes that contribute to mists that degrade air purity and settle on undesired surfaces.
Prior art methods of spray delivery of viscous fluids may involve a high pressure gas to dropletize the flow. The gas flow turbulence acts to break up a low pressure liquid stream. Alternatively, two high pressure streams may be directed to impinge on one another from substantially opposite directions to break up the flow into droplets. These and other techniques for spraying viscous liquids typically result in a fine mist or undesired spray patterns. The fine mist may be desired in some paint spray operations, but can cause problems in other applications where the delivery must be confined to a target area and mists that may be carried by ambient air currents must be minimized.
Thus, there is a need for improvements in the art of spray delivery of high viscosity liquids.